It sucks when you’re trying to vaporize your enemy and your death ray is split in two around a force field, doesn’t it? Just ask Centaurus A.

That’s a big elliptical galaxy only about 11 million light-years from Earth, making it close enough to study in detail. Cen A, as we in the know call it, has a supermassive black hole in its core that’s actively feeding on material around it. That stuff forms a swirling disk of matter that heats up to impossibly high temperatures and blasts out radiation, making Cen A what we call an active galaxy.

The intense magnetic field around the black hole and disk also wind up tightly, focusing twin beams of matter blasting away from above and below the disk. These jets extend for thousands of light-years inside the galaxy and for hundreds of thousands beyond it, and near the black hole the material is being accelerated to about half the speed of light! The energies involved with all this are immense.

So the last place you’d want to be, if you happen to find yourself in the Cen A neighborhood, is in the path of one of those jets. But a new discovery using the Chandra X-Ray Observatory seems to have found some unlucky object in just that situation [link to journal paper].

The image clearly shows the two jets — one aimed more or less in our direction, and the other away from us. A weird effect of relativity, called relativistic beaming, makes the beam headed our way brighter and the one headed away dimmer. But even so, the dimmer counterjet can be seen well enough to study its behavior. Images taken over several years can even show its motion! Half the speed of light is damned fast, and with high enough resolution images changes in the jet can be seen.

Chandra sees X-rays, emitted by material in the jets as they are accelerated by the interior magnetic fields. What a team of astronomers noticed was a peculiar V-shape (labeled C4) in the X-ray data not too far from the main jet. It’s not directly on the line of the jet, but if you look to the upper left; the closer jet flares out and becomes much wider not too far out from the galactic center, so it’s possible the counterjet does as well, but it’s harder to see. If so, that makes it possible this V-shape is the jet itself.

The obvious explanation is that the stream of ridiculously high-speed particles is slamming into something, splitting the jet like a sandbar splits the water in a stream. It’s not clear what could do that. They speculate (and this would be my first guess) that it could be a massive star or stars. These kinds of stars blow out a fierce wind of particles, like the Sun’s solar wind but far, far more powerful. This wind surrounds the star(s) like a bubble, and could deflect the jet. It helps that the wind could be powerfully magnetized as well, acting like a force field around the star(s).

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